(1) Field of the Invention
The subject of the invention concerns a chain transmission used in machine drives.
(2) Description of the Related Art
A book of M. Dudziak “String transmission”, WN PWN, Warsaw 1997, page 246-253 describes a chain transmission consisting of at least two sprockets partially encircled by a chain. A chain consists of a series of links connected through articulated joint. For correct positioning of the chain on the sprockets, a slight overhang is required, which is adjusted periodically or continuously by use of a tensioner. The tensioner allows correct operation of the transmission when the chain lengthens in course of time, mainly because of abrasive wear of its elements. Generally used in chain transmissions are roller pitch chains, consisting of alternately inner and outer links consisting of outer plates, pins, inner plates, sleeves and rollers. By using appropriately lengthened pins and putting outer and inner plates alternately on them, it is possible to build a multiple pitch chain.
Another common type of chain is the toothed roller chain, composed of appropriately shaped plates, each of them having two protrusions on one of their longer edges, which are teeth corresponding in form with the sprocket teeth and building a chain transmission together with a chain. The second edge of the longer edges of the plate is smooth. The plates have two holes in which pins connecting adjoining chain links are located.
From patent abstract no. GB 230839 is known a chain transmission, where the chain has each link equipped with two teeth on one side and is smooth on the other side. The ends of each chain link are formed like the edges of sprockets teeth with which they mate.
From patent abstract no. U.S. Pat. No. 6,440,022 is known a mutual toothed chain containing in longitudinal and crosswise direction alternately laid first and second links. Each first chain link consists of an odd number of connectors laid in the crosswise direction of the chain, and each second chain link consists of even numbers of connectors and pins laid in crosswise direction, where each of them is adjusted to connect two oppositely laid chain links. The connectors of the first chain link and connectors of the second chain link have the same side profile; so that on one side two teeth are laid and the second side is smooth. On each first and second chain link, teeth of the extreme connectors are directed outside and teeth of internal connectors are directed opposite.
From patent abstract no. US 2003/0017896 is known a toothed sprocket having chain transmitting power which consists of links. The sprocket has teeth radially protruding and spreading for a distance of the chain links' length. The chain has two rows of driving and driven, alternately laid links which are connected by pins. Both rows of links alternate along the chain, so that the lines of links in the second row are laid between links from adjoining lines of the first row, and lines of links from the first row are laid between links from adjoining lines of the second row.
From patent abstract no. W095/04889 is known a self-tightening driving chain, in which the length of the moving chain and its tension are constant despite the changing distance between driving and driven sprockets. Tension is achieved by means of appropriately adjusting the off-centre free sprocket. The off-centre free sprocket presents an axis for two arms set in a “V” shape which support the chain drive and linearly separate driven sprockets, which are set in the end of the arms, thereby enabling their appropriate tread. The off-centre free sprocket is encircled by a chain at least in part of free toothed sprocket, both on the side of driving sprocket and on the side of driven sprocket.
The above described solutions do not allow achievement of the same rotational speed of toothed driving and driven sprockets of different diameters while transmitting power through one chain. Development of a chain transmission which will allow driving and driven sprockets of different diameters in a chain transmission to achieve the same rotational speed represents a great improvement in the field of transmissions and satisfies a long felt need of the transmission engineer.